Tight-Polarization SAR Wave Remote Sensing Research

As a new spaceborne polarimetric SAR system,Compact Polarimetric(CP)SAR can obtain abundant polarization information of the target at the same time and realize large-width observation,which has inherent advantages in the field of ocean observation.The working principle of compact polarimetric radar system is to transmit only one polarimetric electromagnetic wave and receive two polarimetric electromagnetic waves at the same time.Compared with full polarimetric SAR,the complexity of system design and maintenance is reduced.The amount of data is half of that of full polarimetric SAR,which expands the range of wave imaging and can obtain more abundant wave information.Previous studies have focused on the construction of pseudo full polarimetric SAR data using compressed polarimetric SAR data,and proposed a variety of related algorithms,but there are still some problems.The sea wave parameters inversion of compact polarimetric SAR is also carried out by using the constructed pseudo full polarimetric SAR data and the existing polarimetric SAR sea wave retrieval algorithm,and the retrieval results are obviously affected by the constructed pseudo full polarimetric error.In view of this,we propose a new method to retrieve ocean wave parameters directly from compact polarimetric SAR data,which does not need to construct pseudo full polarimetric data or estimate complex hydrodynamic modulation transfer function.Firstly,the C-band full polarimetric SAR images of RADARSAT-2 satellite are used to construct the compact polarimetric SAR images corresponding to CTLR and ?/4 modes respectively,and the linear polarization radar cross section with any polarization direction angle is calculated by CTLR and?/4 compact polarimetric SAR modes;Then,the range and azimuth wave slopes are calculated by using CP SAR data directly,and the wave slope spectrum is estimated according to the range and azimuth wave slopes,and the wave parameters are extracted;Finally,comparing the extracted wave parameters with the buoy data of the National Data Buoy Center(NDBC),the results show that the wave retrieval algorithms of the two compact polarimetric SAR models are quite good,and the ?/4compact polarimetric mode is better than the CTLR mode.In order to further explore the influence of sea surface wind speed and radar incidence angle on the retrieval of sea wave parameters,through the comparative analysis of the results of polarimetric SAR sea wave retrieval algorithm,it can be found that CTLR mode and ?/4 mode show relatively high stability in the face of different factors,and CTLR mode has better stability in the process of sea wave retrieval than ?/4 mode.